The gal pal of Michael Douglas’s drug-addled son apparently needs to brush up on her smuggling techniques.

Kelly Sott, the girlfriend of troubled acting-family scion Cameron Douglas, was busted for allegedly trying to pass him 19 tiny baggies of heroin — stuffed into the battery compartment of an electric toothbrush. The delivery happened at the posh Manhattan pad of his mom, Diandra Douglas, sources and court papers revealed yesterday.

The drug fumble occurred Monday morning as court-appointed security guards were watching Cameron, who has been under house arrest at the apartment since his bust for trafficking crystal meth last month, authorities said.

The guards, with him at the home of his mom — dad Michael’s first wife — heard him phone a woman and ask her to bring over some personal items. He was particularly adamant about getting his electric toothbrush, officials said.

He “appeared to be very concerned about when the toothbrush would be delivered,” according to court papers.

The guards immediately became suspicious given his tone — and because one of them recalled that Douglas had received a toothbrush only a few days earlier.

Sott later showed up at the apartment with a black bag. The guards opened it up and examined the toothbrush.

Inside the battery compartment, they found 19 glassine bags “containing a brownish substance that appeared to be heroin,” the federal criminal complaint said.

Drug Enforcement Administration agents were called in, and they field-tested the bags and found that they contained about 7 grams of heroin, authorities said.

Sott, 32, told investigators at the apartment that she didn’t know about the contents of the toothbrush, the complaint said. Sources said she was shaking and sweating when arrested.

The agents eventually brought her back to the Gansevoort Hotel room she had shared with Douglas until he was busted last month with what the feds said was a half-pound of crystal meth — part of his alleged cross-country drug-dealing operation.

Sott had continued to stay in the hotel room after Douglas moved out under the house-arrest agreement.

Investigators said she allowed the DEA agents to search the room, where they found “dozens” of empty bags that appeared to have the same marking as those found in the toothbrush, according to the complaint.

Agents also found several bags filled with what appeared to be heroin, as well as a small amount of marijuana and crystal meth, the complaint said.

New court documents also revealed yesterday that the feds have video evidence allegedly tying Sott to the drug shipment that resulted in Douglas facing at least 10 years — and possibly up to life — in jail.

A weary-looking Sott appeared in Manhattan federal court yesterday, where her lawyer, Jason Yang, did not oppose her being jailed without bail.

Yang told Magistrate Frank Maas that Sott needs medical attention for a “health condition.” She was described by authorities as a heroin user who suffers from hypertension.